Achieve Hint Meaning

[405513470]

"In general, if the percent ionization is less than 5%, the assumption that the amount of lactic acid dissociated in solution is negligible is valid and the answer will be the percent ionization. In this case, the percentage is greater than 5%. Therefore, the percent ionization must be calculated using the quadratic equation instead."
Could someone please explain what they mean by this? Since when is the quadratic equation used for percent ionization. I thought it was just used to find concentrations x.

[Sharlene Duong 3E]

When you are finding x, you can either use an approximation or you can use the quadratic formula. If the concentration of x is less than 5% of the initial concentration, which you find by using the percent ionization ([H+]equilibrium/[HA]initial x 100), then you can use the approximation. If the concentration of x at equilibrium is greater than 5%, then you would have to use the quadratic formula. In order to find percent ionization, you would use the same formula ([H+]equilibrium/[HA]initial x 100). Therefore, using the quadratic formula is sort of implied when finding the percent ionization. Hope this helps!

[Michelle Jeong 1B]

Well to find the percent ionization you need to find the value of x. So if you approximated to find x and then used that value for the % ionization, you need to recalculate the value of x by using the quadratic formula, then use that value to find the % inonization.

[Kevin Zhang 3K]

if the equilibrium x is less than 5% of the original chemical, the -x in "initual -x" would disappear as it is virtually no change but the x from the products would still be calculated for.

[Savannah Licciardello 2C]

Basically it means that you cannot approximate. Generally speaking if the k<10^-3 we can approximate any term like .15-x as simply .15. However in this problem we cannot and must use the full term.

[Naomi Christian 1E]

It means that you cannot deem x negligible, as it is more than 5% ionized. So it is telling you to go back and use the quadratic formula to find x instead.

[Kayla Ziebell 1H]

If x is less than 5% ionization, then when calculating using ICE, you can simplify the math and make an approximation by taking out the "-x" in the equilibrium term. However, if it is more than 5%, then you have to solve using the quadratic equation.

[305769107]

I am a bit confused about this too. Can someone explain it with the context of Achieve #3? I am getting a percent ionization greater than 5%.